Overall, the evidence was of low quality — only 16.5% of the studies had a low risk of bias.

Acupuncture: Out of 45 trials, 2 had a low risk of bias, and 18 reported weight changes of less than 5% and 5 kg. The 2 studies with a low risk of bias showed no or nonsignificant weight loss.
Calcium with vitamin D: Out of 22 trials, 5 had a low risk of bias, and of these, none reported a change in weight.
Chitosan: Out of 9 trials, 1 had a low risk of bias; it reported a weight loss of 2.3 kg over 6 weeks.
Chocolate/cocoa: Out of 6 trials, 1 had a low risk of bias; it reported no change in weight.
Chromium: Out of 6 trials, 3 had a low risk of bias, and of these, only 1 reported a change in weight: a loss of 1.4 kg over 72 days.
Ephedra with caffeine: Out of 31 trials, 10 had a low risk of bias, and of these, 5 reported a change in weight: a loss ranging from 0.3 to 4.9 kg.
Garcinia cambogia: Out of 15 trials, 4 had a low risk of bias, and of these, 2 reported a change in weight: a loss ranging from 1.3 to 3.6 kg.
Green tea: Out of 30 trials, 16 had a low risk of bias, and of these, 2 reported a change in weight: a loss ranging from 1.5 to 1.7 kg.

Guar gum: Out of 5 trials, none had a low risk of bias, and only 1 reported a change in weight: a loss of 2.9 kg over 4 months.
Conjugated linoleic acid (CLA): Out of 31 trials, 5 had a low degree of bias, and of these, 1 reported a change in weight: a loss ranging from 1.5 to 3.0 kg.
Mindfulness: Out of 22 trials, 2 had a low risk of bias, and 6 others reported a weight loss.
Phenylpropylamine (PPA, an appetite suppressant and decongestant no longer sold over the counter in the United States): Out of 5 trials, 1 had a low risk of bias; it reported no change in weight.
Pyruvate: Out of 7 trials, none had a low risk of bias, and 4 reported a weight loss ranging from 0.1 to 1.2 kg.
White kidney bean extract: Out of 7 trials (which lasted 30–60 days and used doses ranging from 445 to 1,000 mg/day), none had a low risk of bias, and 3 reported a weight loss ranging from 0.4 to 2.93 kg .

How strong is the evidence for weight-loss supplements and therapies? Original paper